Hydraulic transmitter-motor unit



Patented Aug. 14, 1951 HYDRAULIC TRANSMITTER-MOTOR UNIT Jesse G.Lindeman, Yakima, Wash, assignor, by mesne assignments, to Deere &Company, Moline, Ill., a corporation of Illinois Application August 9,1948, Serial No. 43,180

Claims. 1 This invention relates to a fluid-pressure drive system andmore particularly to a hydraulic driving system of the type in whichfluid pressure developed by a double-acting reciprocating piston istransmitted to a motor for reciprocating a double-acting piston in themotor. Still more particularly, the invention relates to the adaptationof such system to convert rotary motion into reciprocating motion, as inthe case of a mower or like machine.

2 One of the principal features of the invention resides in theprovision of a system comprising a pump or transmitter unit and a motorunit, each including a pair of opposed cylinders and each including adouble-ended piston carried for reciprocation in the associated pair ofcylinders, with the end portion of one piston operating-in one cylinderand the opposite end portion operating in the opposite cylinder, thetransmitter cylinders being respectively connected to the motorcylinders by means of fluid-pressure-transmitting conduits so that thesystem includes two independent closed fluid circuits, wherebyreciprocation of the transmitter piston will eiiect reciprocation of themotor piston. Another object of the invention is the provision of afluid reservoir connected to the separate circuits in such manner thatthe fluid in these circuits may be replenished from time to time as thenormal pressure or volume in such circuits diminishes because ofleakage, for example. It is still another feature of the invention toconnect the circuits to the reservoir by over-load or pressure-reliefvalves operative in response to abnormally high pressures developed insuch circuits so that the pressure in excess of normal may be exhaustedto the reservoir. It is in connection with this feature of the inventionthat the replenishing means operates to maintain the circuits at theirnormal fixed volumes. A still further feature of the invention residesin means for normally maintaining a quantity of fluid under pressure inthe reservoir so that when the pressure in either circuit falls belowthat in the reservoir, the replenishing means operates to supply anadditional quantity of fluid to that circuit to make up the deficiency.In a preferred form of the invention, the pump and motor are providedwith separate interconnected reservoirs.

In the adaptation of a system of this type for the purpose of drivingthe cutter of a mower or the like, it is recognized that the ordinarymower or like machine is driven by some form of mechanical power trainincluding belts, pulleys, shafts, gears or chains, as in the case of atractor mower in which the cutter bar is driven by a mechanical trainconnected to the tractor power take-off shaft. In the case of atrail-behind or horse-drawn mower, the drive to the cutter bar isaccomplished by a mechanical power train connected to one of the drivingwheels. In either case, the reciprocation of the cutter bar is effectedat relatively high speeds and the mower and the carrying structure towhich it is connected must be constructed to accommodate the vibrationdue to reciprocation, which is of considerable magnitude. According tothe present invention, it is an object to utilize a hydraulic system inplace of a mechanical system, thereby achieving many advantages andeliminating many disadvantages, particularly those due to suchpeculiarities of mower construction as require a relatively large degreeof flexibility between the cutter bar and the carrying structure.v Inthe case of a mower driven by a mechanical power train, provision mustbe made in the power train for accommodating such flexibility, suchprovision usually including necessary universal joints and telescopicshafting, for example. Further, the magnitude of the vibration due toreciprocation of the cutter or sickle may be minimized in the use of afluid drive, since the moving parts may be hydraulically cushioned.

The invention resides in the foregoing objects and features and in othercombinations and arrangements of parts as will more readily appear inthe accompanying drawing and specification and claims appended hereto.

In the drawing, wherein a preferred form and preferred adaptation of theinvention are illustrated by way of example:

Figure 1 is a sectionaland condensed view of the hydraulic drive system;and

Figure 2 is a plan view, which is largely schematic, of atractor-connected mower utilizing the hydraulic unit shown in Figure 1.

The schematic illustration of the mower in Figure 2 is based on thedisclosure of the U. S. patent to Paradise 2,171,761; however, any otherrepresentative type of mower may be modified to adapt the presentinvention thereto. In the present illustration, the mower is of the typeconnected to and supported in part on a vehicle, such as a tractorhaving a main body l0 supported on a pair of transversely spacedtraction wheels II. The mower is designated generally by the numeral I2and is positioned rearwardly of the tractor. The mower includes cuttingmechanism having a laterally extending cutter bar I 3 provided with aninner ground-engaging shoe HI.

The cutting mechanism further includes supporting structure by means ofwhich the mower is carried on carrying structure, which, in the presentcase, includes both the tractor and a rearwardly' extending frame 15.The forward end of the frame is supported on draft or supportingstructure on the tractor, such as the tractor draw bar as indicated at16. The rear end of the frame I5 is carried on a single caster wheel ii.

The means for supporting the forward end of the frame on the tractordrawbar It includes a transverse frame member If! having at the lefthand end thereof a clevis l9 which provides a first pivot on ahorizontal axis and a second pivot 2| on a vertical axis. The connectionbetween the forward end of the frame 15 and the right hand end of theframe member 18 includes a releasable latch designated generally by thenumeral 22. This latch may be of any conventional construction and hasnot been illustrated in detail. As is ordinarily the case with suchlatches, there is included in the latch a pivot 23 on a hori zontal axiscoaxial with the pivot axis of the pivot 20. According to theconstruction just decribed, the mower frame I5 is free to float aboutthe pivot axi 20-23 as the wheels II and ll encounter varying groundcontour. The shoe as of the cutter bar i3 is connected on a longitudinalhortzontal axis at 24 to a yoke 25 which is provided at the outer end ofa laterally extending supporting arm or coupling bar 25, the inner endof which is carried in a bearing 21 rigidly supported on a pair ofcrossed members 28 included in the frame IS. The bearing 27 provides alongitudinal horizontal pivot. The cutter bar l3 thus has flexibilitywith respect to the frame l5 about the horizontal longitudinal pivots 24and 2?. On the other hand, the cutter bar is connected to the frame 15in longitudinally fixed relation with respect thereto, part of the meansaccompli hing this result comprising the arm 26 and another part of suchmeans comprising a rigid connecting link 29 which interconnects the yoke25 and a transverse bar 30 extending across forward portions of theframe l5. The releasable latch mechanism 22 normally holds the cutterbar and frame If in the position illustrated. However, in the event thatthe cutter bar encounters an obstacle impeding its forward travel, thelatch mechanism may release, thus allowing the frame i5, together withthe cutter bar i3 and its supporting structure, to swing rearwardlyabout the vertical pivot 2|, a result that is familiar to those skilledin the art andone that is treated here for the purpose of characterizingthe requirement of r flexibility in a mower and thus emphasizing theimportance in such construction of the use of a system including theunit shown in Figure 2, a description-of which will follow.

Briefly, the fluid system includes a pump or transmitter unit and amotor unit 36 interconnected by a pair of separatefluid-pressure-transmitting conduits 3'! and 38. In the adaptation ofthe fluid driving system to a mower such as that illustrated, thetransmitter unit 35 will be preferably located on the tractor or somerigid frame part associated therewith; and the motor unit will bepreferably located on the mower, particularly the cutter bar of thecutting mechanism. In the present case, the unit 35 is shown as beingcarried on the transverse frame member I8 directly behind the tractor,and the unit 36 is shown as being mounted on the inner shoe It. Thetractor l0 illustrated here has, like the conventional tractor, arearwardly extending power take-off shaft, designated generally by thenu meral til. As will be hereinafter brought out, the power developed bythis rotary shaft is utilized to obtain reciprocation of piston means inthe unit 35. The cutting mechanism is provided with a reciprocatingcutter or sickle 4! which has a cutter or knife head 32 in closeproximity to the motor unit 36. As will be described below,reciprocation of a piston means in the motor 36 is utilized to impartreciprocation to the cutter or knife 4 I.

In the preferred form of the invention illus-' trated in FigureZ, theunit 35 comprises a housing t5 including a fluid reservoir 5% which ispreferably cylindrical and normally closed by a remov able cover l'l.Fluid contained in the reservoir 5 is normally maintained underpressure, and the means for accomplishing this may be in the form of aplunger .8 biased or loaded by a compression spring 49 which surrounds astem 53 connected to the plunger 48 and guided into an aperture in thecap or cover 41. The transmitter includes a pair of opposed cylinders 51and 52, these cylinders preferably being coaxial on opposite sides ofthe central reservoir 46. A double ended piston, indicated generally bythe numeral 53, is carried by the housing for reciprocation in thecylinders 51, the piston 53 having opposite ends or plungers 5d and 55which operate respectively in the cylinders 51 and 52. The means forconverting the high speed rotation of the tractor power take-off shaft43 to reciprocation of the piston 53 comprises a yoke 56 preferablyformed integrally with the piston 53 and intermediate the plunger endportions 54 and 55. A shaft 51 is journaled in the housing 45 and may becarried in bearings of any appropriate construction, the axis of theshaft 57 being normal to the axis of reciprocation of the piston 53.When the unit 35 is mounted in place on the frame member IS, the shaft5? is coaxial with and connected to the tractor power take-off shaft 46,the connection therebetween being accomplished in any suitable manner,the details of which need not be illustrated or described here.

The general design of the motor unit 36' follows that of the unit 35, atleast to the extent that the motor unit is preferably in the form of ahousing '50 having a reservoir portion BI and a pair of opposedcylinders 62 and 63, the cylinders 62 and 63 being preferabl coaxial atopposite sides of the reservoir 8|. The reservoirs 46 and 6! areinterconnected in fluid-interchange relationship by means of a conduit64. The motor unit housing carries for reciprocation therein adoubleended piston 65 which has a pair of opposite end or plungerportions 66 and 6! operating respective in the cylinders 62 and 63. Theintermediate portion of the piston 65 is provided with a yoke 68 which,by means of an arm and roller 69 and Hi, effects oscillation of a shaftH. One end or the shaft 1 projects to a point outside the housing 60 andis keyed or otherwise secured to a driv-- ing arm 12. a pitman 13 to theknife head 42 on the knife or sickle 4|. Reciprocation of the piston 65is thus transmitted to the cutting mechanism of the mower.

The transmitter housing 45 is so constructed that the cylinders 5| and52 communicate respectively with chambers or ports 15 and 16. Similarly,the housing 60 includes chambers 11 and 18 which communicaterespectively with the cylinders 62 and 63. The cylinder 5| and chamber15 are connected by the conduit 3'! to the This arm is in turn connectedby motor chamber I1 and motor cylinder 62. A similar connection iseffected by the conduit 38 between the cylinder 52, chamber 76, chamberI8 and cylinder 32. The design is preferably such that the parts areproportioned as illustrated; that is, the displacement of the pistons54, 55, 66 and 31 is the same. At one side of the two units, thecylinders 5i and 52, the chambers I5 and I1 and the conduit 3'! providea normally closed circuit which contains a fixed volume of fluid foreffectively connecting the pistons 53 and 65, so that movement of thepiston 53 to the left, for example, will result in displacement of thepiston 65 to the right. Likewise, a second independent normally closedcircuit containing a fiXed volume of fluid is provided by the cylinders82 and 63, the chambers I6 and I8 and the conduit 38, whereby movementof the piston 53 to the right will result in displacement of the piston65 to the left. It will be understood, of course, that alternatedisplacement of the piston 65 to the right and left by means of thepiston 53 occurs at relatively high speeds, since the driving means53-5'I for the piston 53 is connected to the tractor power takeoffshaft, the normal operating speed of which is between 500 and 600 R. P.M.

The housing45 is provided with a pair of removable plugs 80 and 8Irespectively in the circuits including the conduits 3? and 38. Theseplugs may be removed for the purpose of initially filling thesecircuits, in addition to which the reservoirs 466I are filled. The plugs80 and 8| may be removed to vent the circuits.

According to the present invention, it is an im-,

portant feature to provide means for maintaining the fixed volume offluid in the circuit 31 or 38. For this purpose, the system includes apair of make-up or replenishing means, indicated generally at 83 and 34.The means 83 preferably includes a passage 84 communicating with thereservoir 46, a passage 85 communicating with the chamber I5, and acheck valve 86 controlling communication between the passages 84 and 85,the check valve 86 being normally closed against the transmission offluid from the reservoir 46 to the circuit including the conduit 31. Thearrangement is such that the check valve 86 will open in response to adecrease of pressure in the circuit 31 below that in the reservoir 46-,whereupon the circuit 3'! may be replenished by fluid from thereservoir. A similar result is obtained by pas- Sages 81 and 88 and acheck valve 89 between the reservoir 46 and the chamber I6.

Another feature of the invention is the provision of overload or reliefvalves, designated here at 90 and 9I, there being one for each circuit31 and 38. The valve means 90 includes a check valve 92 normally biasedto close a port 93 communicating with the chamber 11. The closure of theport 93 by the check valve 92 disconnects the port 93 normally from apassage 94 which leads to the motor reservoir 3| In the event of anabnormal pressure rise in the circuit 31, the valve 92 may open to allowexcess pressure to be exhausted through the port 93 and passage 94 tothe reservoir 6|. A similar arrangement is provided for the othercircuit 38, the valve 9I including a check valve 95 which controlscommunication between a port 96 in the chamber 18 and a passage 91 whichleads to the reservoir 6|.

In order that the piston 65 may reciprocate in the cylinders 62 and 63with a minimum of adverse vibratory eiTect, there is provided hydrauliccushioningmeans at opposite ends of the piston. To this end, the innerend of the cylinder 62 is provided with a counterbore I00 in conimunica=tion via bypass ports IOI and I02 with the reservoir 6|. The counterboreI00 receives a plunger portion I03 provided as an integral part of theleft hand portion of the intermediate part of the piston 55, so that,when the piston 65 moves to the left, the portion I03 will enter thecounterbore I00, thus forcing fluid through the ports IOI and I02 andproviding a hydraulic cushion. A similar arrangement is provided at theother side of the intermediate part of the piston for accomplishingsimilar results when the piston 65 moves to the right, these componentsbeing designated at I05, I06, I01 and I08 and corresponding respectivelyto the components, I 00, IOI, I02, and I 33. As shown in Figure 2, theadaptation of the units 35 and 38 to the mower enables the use offlexible conduits such as hoses for the conduits 37, 33 and 64. Suchflexible conduits readily accommodate variations in the relativepositions of the cutter bar or frame I5 with respect to each other orwith respect to the tractor.

The operation of the system may be summarized briefly as follows:Initially, the circuits 3'! and 38 contain a fixed volume of fluiddetermined for each circuit by the size of the conduit 3! (38) andassociated chambers and cylinders. The reservoir means 46349I will alsocontain a quantity of fluid which will be held under pressure by theplunger 48 and the relatively light spring 49. During normal operationof the system, pressure in either circuit 37 or 38 may drop because ofleakage of fluid or for other reasons. In such event, the appropriatereplenishing valve will operate to supply the necessary additionalquantity of fluid to the efiicient circuit. In the event that the knife4] becomes jammed so as to prevent reciprocation of the piston 65, thepressure in one of the circuits 3'! or 38 will increase abnormally; forexample, let it be assumed that theknife 4! is accidentally jammed inthe position shown in the drawing, thus temporarily locking the piston65 in the position shown; in such case, movement of the piston 53 to theright will increase the pressure in the circuit 38, whereupon theoverload valve 9I will operate to allow this pressure to be exhausted tothe reservoir 6|. Simultaneously with the movement of the piston 53 tothe right, which increases pressure in the circuit 38, there will occura decrease in pressure in the circuit 31, whereupon the replenishingvalve 83 will operate to supply additional fluid to the deficientcircuit. Then, when the piston 53 moves again to the left there will bean abnormal volume of fluid in the circuit 31, which will result in anabnormal pressure rise followed by opening of the overload valve andexhausting of the excess pressure to the reservoir 6| At the same time,the pressure in the circuit 38 will drop and the replenishing valve 84will operate to supply additional fluid to the deficient circuit 38. Inshort, fluid will circulate relatively freely through the valves 83 and04 and relief valves 90 and 9I as long as there is some condition thatprevents reciprocation of the piston 65. In this connection, it shouldbe noted that the springs in the replenishing valves 83 and 84 arerelatively lighter than the springs in the relief valves 96 and 9|, forobvious reasons.

The foregoing description of the preferred embodiment of the inventionis not intended to exclude various changes in the proportions anddispositions of the parts, since the embodiment of the inventiondisclosed is susceptible to. many modifications and alterations, all ofwhich may be made without departing from the spirit and scope of theinvention as defined in the appended claims.

What is claimed is:

1. Fluid-pressure apparatus, comprising: a transmitter unit and a motorunit, each includinga housing provided with a fluid reservoir and a pairof opposed cylinders, each unit further including a double-ended pistoncarried by the housing of said unit for reciprocation, opposite c-nds ofthe piston operating respectively in the cylinders of said unit; meanscarried by the transmitter unit housing and connected to the transmitterpiston for reciprocating said piston; a pair of fluid-pressure-transrnitting conduits re spectively connecting the cylindersof the transmitter unit to the cyiinders of the motor unit, each conduitand its associated transmitter cylin der and motor cylinder providing anormally closed, independent fiuid-pressure circuit of fixed volume, sothat reciprocation of the transmitter piston eiiects reciprocation ofthe motor piston; power take-03 t means carried by the motor unithousing and connected to the motor piston; means in the transmitter unithousing for applying pre sure to the fluid in the transmitter unitreservoir; means interconnecting the reservoirs for fluid interchangetherebetween; a pair of fluid-replenishing means, one between trammitterunit reservoir and each conduit, each of: said means including anormally closed valve arranged to open in response to decrease ofpressure in the associated conduit below that of said transmitter unitreservoir; and a pair of fluidpressure-reliei valves, one between themotor unit riservoir and each conduit and normally close but operativeto open in response to abnormal pressure rise in such conduit to exhaustto said motor unit reservoir.

2. Fluid-pressure apparatus, comprising: a transmitter unit and a motorunit, each including a housing provided with a fluid reservoir and apair of opposed cylinders, each unit further including a double-endedpiston carried by the housing of said unit for reciprocation, oppositeends of the piston operating respectively in the cylinders of said unit;means carried by the transmitter unit housing and connected to thetransmitter piston for reciprocating said piston; a pair offluid-pressure-transmitting conduits respectively connecting thecylinders of the transmitter unit to the cylinders of the motor unit,each conduit and its associated transmitter cylinder and motor cylinderproviding a normally closed, independent fluid-pressure circuit or"fixed volume, so that reciprocation of the transmitter piston eiiectsreciprocation of the motor piston; power take-on means carried by themotor unit housing and connected to the motor piston; means in onehousing for applying pressure to the nuid in the reservoir of thathousing; means in terconnecting the reservoirs for fluid interchangetherebetween; a pair of fluid-replenishing means, one between onereservoir and each conduit, each of said means including a normallyclosed valve arranged to open in response to decrease of pressure in theassociated conduit below that or" said reservoir; and a pair offluid-pressure-relief valves, one between one of the reservoirs and eachconduit and normally closed but operative to open in response toabnormal pressure rise in such conduit to exhaust to said reservoir.

3. Fluid-pressure apparatus, comprising: a transmitter and a motor, eachincluding a fluid reservoir and a pair of opposed cylinders, eachfurther including a double-ended piston carried for reciprocation,opposite ends of the piston operating respectively in the cylinders;means carried by the transmitter and connected to the transmitter pistonfor reciprocating said piston; a pair of fluid-pressure-transmittingconduits respectively connecting the cylinders of the transmitter to thecylinders of the motor, each conduit and its associated transmittercylinder and motor cylinder providing a normally closed, independentfluid-pr'essure circuit of fixed volume, so that reciprocation of thetransmitter piston effects reciprocation of the motor piston; powertake-off means carried by the motor and connected to the motor piston;means interconnect ing the reservoirs for fluid interchange therebetween; a pair of fluid-replenishing means, one between one reservoir andeach conduit, each of said means including a normally closed valvearranged to open in response to decrease of pressure in the associatedconduit below that of said reservoir; and a pair offluid-pressure-relief valves, one between one of the reservoirs and eachconduit and normally closed but operative to open in response toabnormal pressure rise in such conduit to exhaust to said reservoir.

i. A hydraulic power unit, comprising: a trans mitter having a housingproviding a fluid re= servoir and a pair of opposed cylinderscommunicating with and extending from said reservoir, a pair of pistonsrespectively in said cylinders, and rotary input means in the reservoirconnected to reciprocate said pistons; a motor having a housingproviding a fluid reservoir and a pair of opposed cylinderscommunicating therewith and extending therefrom, pistons respectively inthe motor cylinders, and rotary output means in the motor reservoir andoperatively connected to the motor pistons; fluid-transmitting conduitsrespectively connecting the transmitter cylinders to the motorcylinders; fiuid make-up means connected between the transmitterreservoir and each of the conduits; pressure-relief means connectedbetween each conduit and the motor reservoir; and a fluid-transmittingconduit separate from the aforesaid conduits and interconnecting thereservoirs.

5. A hydraulic power unit, comprising: a transmitter having a housingproviding a fluid reservoir and a pair of opposed cylinderscommunicating with and extending from said reservoir, each of saidcylinders having at its outer end remote from said reservoir a fluidport formed in the housing, a pair of pistons respectively in saidcylinders for alternately discharging and receiving fluid respectivelythrough said ports, rotary input means in the reservoir and operativelyconnected to reciprocate said pistons, and fluid make-up means betweenthe reservoir and said ports, including a pair of passages formed insaid housing and respectively by-passing the pistons and communicatingthe reservoir and said ports; a motor having a housing providing a fiuidreservoir and a pair of opposed cylinders communicating therewith andextending therefrom, each of said motor cylinders having a fluid port atits outer end remote from said motor reservoir, pistons respectively inthe motor cylinders, and rotary output means in the motor reservoir andoperatively connected to the motor pistons; fluid-transmitting conduitsrespectively connecting the transmitter ports to the motor ports;pressure-relief means in the motor housing including a pair of passagesrespectively by-passing the motor pistons and connecting the motor res-JESSE G. LINDE'MAN.

. 1 REFERENCES CITED The following references are of record in the fileof this patent:

UNITED STATES PATENTS Number Name Date 568,736 Brown Oct. 6, 18961,301,485 Mueller Apr. 22, 1909 Number Number Name Date Horste Dec. 19,1933 Kerr Feb. 22, 1938 Nardone June 18, 1940 Warner June 16, 1942Andrews May 13, 1947 Hughes Mar. 16, 1948 Geiger June 15, 1948 FOREIGNPATENTS Country Date Great Britain Nov. 5, 192 6

